This invention relates to an image forming apparatus utilizing an electrophotographic method for example, and in particular, to an image forming apparatus equipped with a lubricant coating mechanism for coating a lubricant utilizing a brush roller for an image carrying body such as an image forming body and an intermediate transfer member on which a toner image is formed.
At present, in a certain kind of image forming apparatus utilizing, for example, an electrophotographic method, for the reason of improving the transfer performance and the development performance for example, when a transfer process is carried out, it is put into practice to carry out an image formation operation, for example, in a state that the mutual relation between the surface energy of both the image carrying body carrying a toner image and the image transfer member (for example, a transfer sheet, etc.) to have a toner image transferred, or the mutual relation between the angles of contact for pure water at the surface of both the members are adjusted so as to satisfy a specified relation, by the practice of a surface reforming processing for the image carrying body (image forming body for example) carrying a toner image.
Further, it is put into practice, in an image forming apparatus utilizing an intermediate transfer method, to set a state that the mutual relation between the respective surface properties of both the image carrying body carrying a toner image and the intermediate transfer member, and the mutual relation between the respective surface properties of both the intermediate transfer member and the transfer sheet satisfy a specified relation (refer to the publications of the unexamined patent applications H08-211755 and H07-52263, and U.S. Pat. No. 5,732,314, for example). For example, to state the magnitude relation on the angle of contact for pure water, it is necessary for the magnitude relation to satisfy the relation: image forming body (>intermediate transfer member)>transfer sheet.
For a concrete means for adjusting the surface property, for example, coating of a lubricant, adjustment of the surface roughness, and selection of the material of the structural member such as the image forming body can be cited.
It is generally considered that, by a surface reforming treatment of the structural members being done in such a manner as to satisfy the above-mentioned specified relation in the beginning of image formation operations made over a long period of time, to state it concretely, for example, by the continuous coating of a lubricant with a coating amount adjusted to satisfy the specified relation, the relation that is set at the early stage of the image formation operations over a long period of time is maintained irrespective of the number of times of image formation operations.
However, actually, in the case where after image formation operations have been carried out for a long period of time, an image formation operation is further carried out, a problem that the transfer ability of an image itself is lowered to cause an inside-void phenomenon be produced, which makes it difficult to form a high-quality image.
As regards such a problem, although it becomes different in accordance with the operation conditions of the image forming apparatus etc. for example, there is a case where the problem occurs at a point of time the number of times of image formation has exceeded ten thousand times.